【摘要】 为提高核磁共振找水仪的接收信号质量,结合核磁共振信号微弱、噪声干扰严重的特点,根据微弱信号检测技术、电路低噪声设计和传输线基本原理,着重分析了地面核磁共振找水仪传输线与前置放大器的匹配问题;给出了相应的噪声匹配方案,从噪声和干扰角度对放大器内各模块的级联顺序进行了设计。通过实验验证了该核磁共振找水仪的有效性,监测到的最小信号在470 nV左右。经过波形数据多次叠加,进一步提高了信噪比,整体仪器能检测核磁共振的最小信号为50 nV。更多还原

【Abstract】 In order to improve the quality of receiving signal for surface nuclear magnetic resonance instrument for groundwater,considering the fact that nuclear magnetic resonance signal is very faint,and often heavily affected by noises and interferences,according to faint signals detection technology,design of low noise circuit and transmission line principle,this thesis focuses on the analysis of matching transmission lines and the preamplifier of the surface nuclear magnetic resonance instrument for groundwater and points out the corresponding solution for noise matching.It gives a design for the cascade order of all blocks of the amplifier from the angle of noise and interference.The performance of NMR(Nuclear Magnetic Resonance) instrument was proved by outdoor experiments,and successfully detect minimum NMR signal at about 470 nV steadily.By adding up more wave signal,we can further reduce noise within signal.The minimum signal we can detect using our nuclear magnetic resonance instrument is 50 nV.更多还原